Author Topic: transmission humming  (Read 188 times)

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kartone

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transmission humming
« on: May 20, 2020, 12:13:17 PM »
Due to a diff problem (broken tooth) had the diff and while at it the transmission rebuilt last year.
Since then there has been a humming noise from the transmission in 4th gear only, more pronuonced while cruising (no load).
Any inkling as to what the source can be? Many thanks.
82 GTV6 split-dash
80 Alfetta GTV

sportiva

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Re: transmission humming
« Reply #1 on: May 20, 2020, 03:22:51 PM »
Hi kartone
What tooth was broken in the diff assembly was it the crownwheel the pinion or one of the planetry gears and when the gearset was "rebuilt" was it synchros and hubs or did you have bearings replaced aswell.
You say the humming is only in 4th gear that would suggest to me a problem with the 4th gear synchro assembly or the bearing of the assembly that rotates on the main shaft. The individual gears rotate freely on the main shaft untill a gear is selected then the synchro assembly it's hub and the mainshaft are locked together, that is when the load is at it's highest for the selected gear. but there are different loads, under acceleration and constant throttle or engine braking when slowing down.
So under load 4th gear is complaining, the only way to assess the noise is to dissemble the gearset and check each component for unusual wear or damage.

Cheers
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kartone

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Re: transmission humming
« Reply #2 on: May 21, 2020, 12:59:11 PM »
Thanks Sportiva. When I'll get a chance I'll have it diagnosed by the the workshop that did the repair / reconditioning of the transaxle.
82 GTV6 split-dash
80 Alfetta GTV